An air volume control module for use with a vehicular air conditioning apparatus includes a circuit board including a control circuit for controlling the rotational speed of the blower of the vehicular air conditioning apparatus, a heat sink connected to the circuit board and including a fin for radiating heat generated by the circuit board, and a base housing surrounding the circuit board, the heat sink being inserted in the base housing with the fin projecting from the base housing. The base housing is mounted on the heat sink only by a locking finger. Either one of the base housing and the fin of the heat sink has a protective projection having a heightwise dimension greater than that of the locking finger.